Method and apparatus for the automatic manufacture of portions of a given length of strip material having a repetitively patterned surface
The present invention relates to method and apparatus for the automatic manufacture of portions of a given length of strip material printed or embossed with a repetitive pattern in the longitudinal direction of the strip material. Such portions include venetian blind slats and panels for wall and ceiling coverings and for shutters, awnings and sun louvres. 
     Venetian blinds are manufactured with a variety of decorations and finishes, often applied to the slats thereof, which, being formed of a substantially flat or slightly crowned material, are easily printed upon. The slats are usually cut from a continuous strip material and fed straight into an automatic assembling machine. A repetitive design is usually applied to the continuous strip before it is cut into slats and the slats assembled. Similarly predetermined lengths of profiled material are cut before these are assembled into a surface or surface covering for building walls or openings, such as wall or ceiling coverings. If the repetition length of the pattern, for example, 1000 mm, is similar but not the same as the length of each slat, in the case of a venetian blind for example, 1010 mm, the assembled blind shows an additional secondary pattern, in this case a slanting pattern, between repetitions of the preprinted pattern on adjacent slats. This secondary pattern is often undesirable, especially in the case where the preprinted pattern is a marble or wood grain effect, and spoils the visual effect of the preprinted pattern. One method of avoiding such a secondary pattern is to scramble the slats by hand before they are fed into an automatic blind assembly machine. However, such a process is time consuming and expensive and negates the advantages of having an automatic combined cutting and assembly machine. 
     It may also be desirable for the assembled blind to show a secondary pattern different from that which would occur if the cut slats were simply assembled in the order they left the cutting machine Similar considerations could apply in the production of wall and ceiling panels and for awning and sun louvre panels which are decorated with a repetitive pattern. 
     According to the present invention there is provided a method for the automatic manufacture of a predetermined number of portions of a given length of strip material from a supply of strip material having a patterned surface, with the pattern being repetitive in the longitudinal direction of the strip material, said method comprising the steps of: 
     progressively feeding said strip material to a cutting unit; 
     cutting first sections, each of said given length, from said strip of material; 
     cutting second sections from parts of said strip material immediately following at least some of said cut-off first sections, in a controlled manner, to allow the varying of the length of each of said second sections individually, to provide a controlled positioning of the repetitive pattern along the length of the subsequently cut first sections; 
     rejecting said second sections; and 
     removing said first sections for further handling. 
     By using the method of the present invention, secondary patterns in the assembled blind or assembled panelling, for example, may be eliminated or modified as desired to obtain a pleasing finish. The cutting of the respective second sections in respect of the repetitive pattern of the strip material is automatically controlled and performed so as to avoid or to the contrary arrange for a secondary pattern to appear in a direction transverse to the longitudinal direction of subsequently produced first sections upon arrangement thereof in the same sequence into parallel side by side relation to form a preferably decorative covering surface. This may be done without substantially slowing down and without major modification of the subsequent further handling such as an assembly process, in the case of the manufacture of venetian blinds. 
     Also according to the invention there is provided a strip material cutting apparatus for cutting portions of a given length of strip material from a supply of strip material having a patterned surface, with the pattern being repetitive, in the longitudinal direction of the strip material, said apparatus comprising: 
     feed means for feeding said strip material; 
     interrupting means for interrupting feeding of said strip material; 
     cut-off means for cutting said strip of slat material into first and second cut sections; 
     rejection means for rejecting said second cut sections; 
     removing means for removing first cut sections for further handling; and 
     control means connected to said interrupting means, said cut-off means, said removing means and said rejection means said control means being effective to control said interrupting means, said cut-off means, said removing means and said rejection means so as to cut first sections of a first predetermined length from said strip of material and remove said first sections and to cut said second sections from said strip of slat material and reject said second sections, to provide a controlled positioning of the repetitive pattern along the length of the cut first sections. 
     When manufacturing panelling, the cutting of the second sections may, if desired, be controlled and performed so that the differences in pattern of at least a certain number of subsequent first sections creates a specific predetermined decorative composition when said certain number of subsequent first sections are parallely arranged to form a surface. 
     The second cut sections may have a predetermined fixed length, or have a variably or random length. Furthermore a variably, random or predetermined number of such second sections may be cut between adjacent first sections. If it is desired to eliminate any secondary pattern in the assembled blind, or panelling, the second sections are cut with random length, or a random number are cut, or possibly both. If a particular secondary pattern is desired the length and number of the second sections cut may be fixed or may vary according to a predetermined formula. 
     The rejected second sections may either be scrapped or may in some cases be recycled into the production of the continuous strip or might alternatively be used as samples for promotional purposes. 
     In order that the present invention may more readily be understood, the following description is given, merely by way of example, reference being made to the accompanying drawings in which: 
     FIG. 1 is a schematic view showing how slats are cut from a continuous strip of slat material in a conventional venetian blind assembly apparatus. 
     FIG. 2 is a front elevation of a conventional venetian blind assembly apparatus. 
     FIG. 3 is a front elevation of a first embodiment of the present invention, using a modified disc section of a conventional apparatus. 
     FIG. 4 is a front elevation of a second embodiment of the present invention. 
     FIG. 5 is a side elevation of a cut off die modified according to the first or second embodiment of the present invention. 
     FIG. 6 is a partly cross-sectioned side view of a left punch die of the first embodiment of the present invention. 
     FIG. 7 is a front view of an alternative type of assembly apparatus incorporating a third embodiment of the present invention. 
     FIG. 8 is a front view of a cut off die of the third embodiment of the present invention. 
     FIG. 9 is a schematic diagram showing how slats are cut from a continuous strip of slat material in one form of venetian blind assembly machine according to the present invention. 
     FIG. 10 is an enlarged cross-section along line X--X of FIG. 5. 
    
    
     Referring to FIG. 2, a conventional venetian blind assembly machine includes a strip supply section 7, a forming section 8 for profiling the strips, an accumulator 8a, a die section 9 and a lacing section 10. The die section 9 includes a left punch die 12, a cut off die 13 and a right punch die 14. As can be seen in FIGS. 3 and 4 strip material is fed by feed means in the form of feed roller shown schematically at 7a. 
     The normal operation of a conventional venetian blind assembly will be described with reference to FIGS. 1 and 2. 
     It can be seen that the left-hand punch die 12, the cut-off die 13 and the right-hand punch die 14 are all activated simultaneously to cut off a slat 1 while punching the left-end hole 4 of slat 1 and the right-end hole 5 of the next slat 2. The slat feed roller is stopped and the cut-off slat is fed out of the dies by a feed-out motor and fed to the lacing section, which comprises a number of appropriately activated lacing stations. The feed roller is then restarted and the continuous strip of slat material fed until it reaches a first stop. The right-hand punch die 14 is then activated separately to punch an intermediate hole 6 in the slat. This procedure is repeat, until the appropriate number of intermediate holes for the length of slat desired have been punched. When the continuous strip material has been fed a length equivalent to one slat, all three dies are activated simultaneously to cut off slat 2 and punch the left-end hole 4 of this slat and the right-end hole 5 of the slat 3, the process now repeats. In this conventional venetian blind assembly machine, the two punch dies 12, 14 and the cut-off die 13 are all activated by a single camshaft similar to camshaft 18 of FIG. 3. Crank 15 is associated with camshaft 18 to operate the dies 12a, 13a and 14 via a drive shaft (not shown). The cut strip is removed by downstream feed means 24b to the lacing section 10. 
     In a first embodiment of the present invention as generally illustrated in FIG. 3, the following modifications are made to a conventional apparatus: 
     punch die 12a is provided with a solenoid activated mechanism 17, see FIG. 6; 
     cut-off die 13a is milled at its lower die part 27, as indicated at 28, to reject and facilitate the dropout of short pieces of slat material and is provided with a solenoid activated stop mechanism 21, see FIGS. 5 and 10. This acts as an interrupting means to interrupt feed of the strip material. 
     The control system shown schematically at 100 for this machine is also modified. 
     In the first embodiment, the second sections are of a fixed predetermined length, equal to the distance 22, between the cut-off nipple 26 and the stop mechanism 21 in FIG. 10, and the control system 100 is adapted to cause the cut-off die 13a to cut a variable or random number of second sections between adjacent first sections which form the slats. 
     The operation of this apparatus in a random pattern mode will be described with reference to FIG. 9. At the end of slat 32 and beginning of slat 33, all three dies are activated simultaneously to punch the right-end hole 5 of slat 32, the left-end hole 4 of slat 33 and to cut off slat 32. As the strip material is fed, punch die 14 is activated twice at appropriate locations to punch the intermediate holes of slats 33. At this point dies 12a, 13a are disengaged from the camshaft device by a clutch 16. At the end of slat 33, cut-off die 13a and punch die 14 are activated to punch the end hole of slat 33 and cut it off. Cut-off die 13a and the stop mechanism 21, are activated to cut off a single short piece of slat material 31. Punch die 12a, cut-off die 13a and the stop mechanism 21 are then activated together to cut off a further short piece 31 and to punch the end hole of slat 34. Punch die 14 is then activated twice again at appropriate points to cut the intermediate holes of slat 34. At the end of slat 34, cut-off die 13a and punch die 14 are activated to cut the end hole 4 of slat 34, and to cut slat 34 off the continuous strip of slat material. Cut-off die 13a and the stop mechanism 21 are then activated four times to cut off four short pieces of slat material 31. Next punch die 12a, cut-off die 13a, and the stop mechanism 21 are activated to cut off a fifth short piece of strip material and punch the left-end hole of slat 35. 
     As can be readily seen, the number of short pieces of slat material 31 cut off between adjacent slats may be easily varied in a random manner so as to eliminate any secondary patterns in the assembled blind. 
     In the second embodiment of the present invention, of FIG. 4, the cut-off die 13a is milled and provided with a solenoid activated stop mechanism 21 as before, see FIGS. 5 and 10. However, the camshaft is provided with two solenoid activated clutches 19, 20 placed either side of the cut-off die 13a. This embodiment then operates as described above. The left-hand punch die 12 can remain substantially unmodified. 
     The third embodiment of the present invention, shown in FIG. 7 in which previously used numerals denote like parts, has an electrically activated cut-off die 23, which is controlled separately from the punch dies 24, which are driven by a camshaft 25, it is therefore only necessary to mill the cut-off die 23 and add a stop mechanism comparable to the mechanism of the previous embodiments. The right-hand most or downstream of the punch dies 24 has associated therewith a feed means 24a which acts to draw the strip material through the apparatus. The feed means 24a thus act firstly as means to feed the strip material to punches 24 and second as withdrawal means to feed the cut strip to section 10. The cut-off die 23, shown in FIG. 8, includes a cut-off nipple 26a, a lower die part 27a from which a section 28a is milled out. To this is added a swiveling end stop 29 activated by a solenoid 30. This embodiment may then cut off short portions of slat material of length equal to the distance 22a, and to adapt the control system in order for this apparatus to function according to the present invention. 
     The end stop shown, is merely one example of the many varieties of end stops that might be employed in an embodiment of the invention; it would also be possible to position the end stop at any position between the cut-off and the first lacing station, or to employ several end stops, or even an end stop of variable position. The end stop might also be hydraulically or pneumatically controlled rather than electrically operated. 
     Alternatively, or additionally, the feed means could be controlled to interrupt the feeding of the strip material e.g. by having a controlled operation of a feed motor or of a clutch or of the position of feed rollers (or a linearly movable feed member) into or out of contact with the strip material. 
     Although the invention has been generally described and explained with reference to a venetian blind slat cutting apparatus it should be understood that the inventive concept is not limited to this particular field of application. Specifically the production of profiled members or panels for forming ceilings, walls, awnings, shutters and sun louvres are all within the scope of the invention.